#include <stdio.h>

int main(int argc, char const *argv[])
{
	//1.空指针:给指针变量赋值为NULL
	//2.NULL就是数字0
    int *p = NULL;
    int a = 11;
    p = &a;

    if (NULL == 0)
    {
    	printf("%s\n", "验证NULL就是数字0");
    }

    if (p != NULL)
    {
    	*p = 100;
    }
    printf("a=%d\n", a);

	return 0;
}